1. Field of the Invention
The present invention relates to a method for manufacturing photoelectric conversion devices using a microcrystalline semiconductor as a photoelectric conversion layer.
2. Description of the Related Art
To deal with global environmental issues in recent years, the market for photoelectric conversion devices such as residential photovoltaic systems has expanded. As photoelectric conversion devices, devices using a single-crystal or polycrystalline silicon wafer which has high conversion efficiency have been used in practice. The photoelectric conversion devices are manufactured using single-crystal or polycrystalline silicon which is cut out from a large silicon ingot. However, it takes a long time to manufacture large silicon ingots, which deteriorates productivity, and since the supply of silicon raw materials is limited, the supply of silicon ingots is insufficient and cannot deal with the expansion of the market.
Photoelectric conversion devices using amorphous silicon have been developed, and reduction of cost seems possible therewith. However, a problem of light deterioration has not been overcome, and thus the photoelectric conversion devices using amorphous silicon have not been commonly used. In addition, although a high-frequency plasma CVD method for manufacturing amorphous silicon can form an film over a large area at low temperature, which can make conversion efficiency of a photoelectric conversion device using amorphous silicon as a photoelectric conversion layer be equal to or greater than 10%; light deterioration called Staebler-Wronski effect can not be overcome. Therefore, development of photoelectric conversion devices has been proceeding, in which microcrystalline silicon, which is crystal silicon and a film of which can be manufactured by a plasma CVD method, is used as a photoelectric conversion layer (for example, refer to Reference 1: Japanese Published Patent Application No. 2000-277439).
As for a crystal silicon film formed by a plasma CVD method and a photoelectric conversion device using the crystal silicon film, photoelectric conversion devices using a microcrystalline semiconductor such as a semi-amorphous semiconductor or a semicrystalline semiconductor, which is different from an amorphous semiconductor and a crystalline semiconductor, were reported by the inventors of the present invention (for example, refer to References 2 and 3: Examined Patent Application Publication No. H2-53941 and Examined Patent Application Publication No. S62-62073).